The present invention relates to a process for the preparation of compounds which are therapeutically active in the central nervous system.In one aspect, the invention relates to a process for the preparation of compounds of the general formula (I): wherein HA is a pharmaceutically acceptable acid and R1-R4 are each independently selected from the group consisting of hydrogen, halogen, C1-C6-alkyl, C1-C6-alkoxy, and di-C1-C6-alkylamino-C2-C6-alkoxy. The invention also relates to the use of said compound to manufacture a medicament for the treatment of a serotonin-related disorder.